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 STOW(8)                                                             STOW(8)
                                28 March 1998

      stow - software package installation manager

      stow [options] package...

      This manual page describes GNU Stow 1.3.3, a program for managing the
      installation of software packages. This is not the definitive
      documentation for stow; for that, see the info manual.

      Stow is a tool for managing the installation of multiple software
      packages in the same run-time directory tree. One historical
      difficulty of this task has been the need to administer, upgrade,
      install, and remove files in independent packages without confusing
      them with other files sharing the same filesystem space. For instance,
      it is common to install Perl and Emacs in /usr/local.  When one does
      so, one winds up (as of Perl 4.036 and Emacs 19.22) with the following
      files in /usr/local/man/man1: a2p.1; ctags.1; emacs.1; etags.1;
      h2ph.1; perl.1; and s2p.1.  Now suppose it's time to uninstall Perl.
      Which man pages get removed?  Obviously perl.1 is one of them, but it
      should not be the administrator's responsibility to memorize the
      ownership of individual files by separate packages.

      The approach used by Stow is to install each package into its own
      tree, then use symbolic links to make it appear as though the files
      are installed in the common tree. Administration can be performed in
      the package's private tree in isolation from clutter from other
      packages.  Stow can then be used to update the symbolic links. The
      structure of each private tree should reflect the desired structure in
      the common tree; i.e. (in the typical case) there should be a bin
      directory containing executables, a man/man1 directory containing
      section 1 man pages, and so on.

      Stow was inspired by Carnegie Mellon's Depot program, but is
      substantially simpler and safer. Whereas Depot required database files
      to keep things in sync, Stow stores no extra state between runs, so
      there's no danger (as there was in Depot) of mangling directories when
      file hierarchies don't match the database. Also unlike Depot, Stow
      will never delete any files, directories, or links that appear in a
      Stow directory (e.g., /usr/local/stow/emacs), so it's always possible
      to rebuild the target tree (e.g., /usr/local).

      A ``package'' is a related collection of files and directories that
      you wish to administer as a unit--e.g., Perl or Emacs--and that needs
      to be installed in a particular directory structure--e.g., with bin,
      lib, and man subdirectories.

      A ``target directory'' is the root of a tree in which one or more
      packages wish to appear to be installed. A common, but by no means the

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      only such location is /usr/local.  The examples in this manual page
      will use /usr/local as the target directory.

      A ``stow directory'' is the root of a tree containing separate
      packages in private subtrees. When Stow runs, it uses the current
      directory as the default stow directory. The examples in this manual
      page will use /usr/local/stow as the stow directory, so that
      individual packages will be, for example, /usr/local/stow/perl and

      An ``installation image'' is the layout of files and directories
      required by a package, relative to the target directory. Thus, the
      installation image for Perl includes: a bin directory containing perl
      and a2p (among others); an info directory containing Texinfo
      documentation; a lib/perl directory containing Perl libraries; and a
      man/man1 directory containing man pages.

      A ``package directory'' is the root of a tree containing the
      installation image for a particular package. Each package directory
      must reside in a stow directory--e.g., the package directory
      /usr/local/stow/perl must reside in the stow directory
      /usr/local/stow.  The ``name'' of a package is the name of its
      directory within the stow directory--e.g., perl.

      Thus, the Perl executable might reside in
      /usr/local/stow/perl/bin/perl, where /usr/local is the target
      directory, /usr/local/stow is the stow directory, /usr/local/stow/perl
      is the package directory, and bin/perl within is part of the
      installation image.

      A ``symlink'' is a symbolic link. A symlink can be ``relative'' or
      ``absolute''. An absolute symlink names a full path; that is, one
      starting from /.  A relative symlink names a relative path; that is,
      one not starting from /.  The target of a relative symlink is computed
      starting from the symlink's own directory. Stow only creates relative

      The stow directory is assumed to be the current directory, and the
      target directory is assumed to be the parent of the current directory
      (so it is typical to execute stow from the directory /usr/local/stow).
      Each package given on the command line is the name of a package in the
      stow directory (e.g., perl).  By default, they are installed into the
      target directory (but they can be deleted instead using `-D').


      --no Do not perform any operations that modify the filesystem; merely
           show what would happen. Since no actual operations are performed,
           stow -n could report conflicts when none would actually take
           place (see ``Conflicts'' in the info manual); but it won't fail

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           to report conflicts that would take place.


           Do not exit immediately when a conflict is encountered. This
           option implies `-n', and is used to search for all conflicts that
           might arise from an actual Stow operation. As with `-n', however,
           false conflicts might be reported (see ``Conflicts'' in the info

      -d DIR

           Set the stow directory to DIR instead of the current directory.
           This also has the effect of making the default target directory
           be the parent of DIR.

      -t DIR

           Set the target directory to DIR instead of the parent of the stow


           Send verbose output to standard error describing what Stow is
           doing. Verbosity levels are 0, 1, 2, and 3; 0 is the default.
           Using `-v' or `--verbose' increases the verbosity by one; using
           `--verbose=N' sets it to N.


           Delete packages from the target directory rather than installing


           Restow packages (first unstow, then stow again). This is useful
           for pruning obsolete symlinks from the target tree after updating
           the software in a package.


           Show Stow version number, and exit.

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           Show Stow command syntax, and exit.

      The default action of Stow is to install a package. This means
      creating symlinks in the target tree that point into the package tree.
      Stow attempts to do this with as few symlinks as possible; in other
      words, if Stow can create a single symlink that points to an entire
      subtree within the package tree, it will choose to do that rather than
      create a directory in the target tree and populate it with symlinks.

      For example, suppose that no packages have yet been installed in
      /usr/local; it's completely empty (except for the stow subdirectory,
      of course). Now suppose the Perl package is installed.  Recall that it
      includes the following directories in its installation image: bin;
      info; lib/perl; man/man1.  Rather than creating the directory
      /usr/local/bin and populating it with symlinks to
      ../stow/perl/bin/perl and ../stow/perl/bin/a2p (and so on), Stow will
      create a single symlink, /usr/local/bin, which points to
      stow/perl/bin.  In this way, it still works to refer to
      /usr/local/bin/perl and /usr/local/bin/a2p, and fewer symlinks have
      been created. This is called ``tree folding'', since an entire subtree
      is ``folded'' into a single symlink.

      To complete this example, Stow will also create the symlink
      /usr/local/info pointing to stow/perl/info; the symlink /usr/local/lib
      pointing to stow/perl/lib; and the symlink /usr/local/man pointing to

      Now suppose that instead of installing the Perl package into an empty
      target tree, the target tree is not empty to begin with. Instead, it
      contains several files and directories installed under a different
      system-administration philosophy. In particular, /usr/local/bin
      already exists and is a directory, as are /usr/local/lib and
      /usr/local/man/man1.  In this case, Stow will descend into
      /usr/local/bin and create symlinks to ../stow/perl/bin/perl and
      ../stow/perl/bin/a2p (etc.), and it will descend into /usr/local/lib
      and create the tree-folding symlink perl pointing to
      ../stow/perl/lib/perl, and so on. As a rule, Stow only descends as far
      as necessary into the target tree when it can create a tree-folding

      The time often comes when a tree-folding symlink has to be undone
      because another package uses one or more of the folded subdirectories
      in its installation image. This operation is called ``splitting open''
      a folded tree. It involves removing the original symlink from the
      target tree, creating a true directory in its place, and then
      populating the new directory with symlinks to the newly-installed
      package and to the old package that used the old symlink. For example,

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      suppose that after installing Perl into an empty /usr/local, we wish
      to install Emacs.  Emacs's installation image includes a bin directory
      containing the emacs and etags executables, among others. Stow must
      make these files appear to be installed in /usr/local/bin, but
      presently /usr/local/bin is a symlink to stow/perl/bin.  Stow
      therefore takes the following steps: the symlink /usr/local/bin is
      deleted; the directory /usr/local/bin is created; links are made from
      /usr/local/bin to ../stow/emacs/bin/emacs and ../stow/emacs/bin/etags;
      and links are made from /usr/local/bin to ../stow/perl/bin/perl and

      When splitting open a folded tree, Stow makes sure that the symlink it
      is about to remove points inside a valid package in the current stow
      directory.  Stow will never delete anything that it doesn't own.  Stow
      ``owns'' everything living in the target tree that points into a
      package in the stow directory. Anything Stow owns, it can recompute if
      lost. Note that by this definition, Stow doesn't ``own'' anything in
      the stow directory or in any of the packages.

      If Stow needs to create a directory or a symlink in the target tree
      and it cannot because that name is already in use and is not owned by
      Stow, then a conflict has arisen. See ``Conflicts'' in the info

      When the `-D' option is given, the action of Stow is to delete a
      package from the target tree. Note that Stow will not delete anything
      it doesn't ``own''. Deleting a package does not mean removing it from
      the stow directory or discarding the package tree.

      To delete a package, Stow recursively scans the target tree, skipping
      over the stow directory (since that is usually a subdirectory of the
      target tree) and any other stow directories it encounters (see
      ``Multiple stow directories'' in the info manual). Any symlink it
      finds that points into the package being deleted is removed. Any
      directory that contained only symlinks to the package being deleted is
      removed. Any directory that, after removing symlinks and empty
      subdirectories, contains only symlinks to a single other package, is
      considered to be a previously ``folded'' tree that was ``split open.''
      Stow will re-fold the tree by removing the symlinks to the surviving
      package, removing the directory, then linking the directory back to
      the surviving package.

      The info manual ``Stow 1.3.3: Managing the installation of software
      packages'' by Bob Glickstein, Zanshin Software, Inc.

      Please report bugs in Stow using the Debian bug tracking system.

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 STOW(8)                                                             STOW(8)
                                28 March 1998

      Currently known bugs include:

      *    The empty-directory problem. If package FOO includes an empty
           directory--say, FOO/BAR--then:

           1.  if no other package has a BAR subdirectory, everything's

           2.  if another stowed package, QUUX, has a BAR subdirectory, then
           when stowing, TARGETDIR/BAR will be ``split open'' and the
           contents of QUUX/BAR will be individually stowed. So far, so
           good. But when unstowing QUUX, TARGETDIR/BAR will be removed,
           even though FOO/BAR needs it to remain. A workaround for this
           problem is to create a file in FOO/BAR as a placeholder. If you
           name that file .placeholder, it will be easy to find and remove
           such files when this bug is fixed.

      *    When using multiple stow directories (see ``Multiple stow
           directories'' in the info manual), Stow fails to ``split open''
           tree-folding symlinks (see ``Installing packages'' in the info
           manual) that point into a stow directory which is not the one in
           use by the current Stow command. Before failing, it should search
           the target of the link to see whether any element of the path
           contains a .stow file. If it finds one, it can ``learn'' about
           the cooperating stow directory to short-circuit the .stow search
           the next time it encounters a tree-folding symlink.

      This man page was constructed by Charles Briscoe-Smith from parts of
      Stow's info manual. That manual contained the following notice, which,
      as it says, applied to this manual page, too. The text of the section
      entitled ``GNU General Public License'' can be found in the file
      /usr/share/common-licenses/GPL on any Debian GNU/Linux system. If you
      don't have access to a Debian system, or the GPL is not there, write
      to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
      Boston, MA, 02111-1307, USA.

           Software and documentation Copyright (C) 1993, 1994, 1995, 1996
           by Bob Glickstein <>.

           Permission is granted to make and distribute verbatim copies of
           this manual provided the copyright notice and this permission
           notice are preserved on all copies.

           Permission is granted to copy and distribute modified versions of
           this manual under the conditions for verbatim copying, provided
           also that the section entitled ``GNU General Public License'' is
           included with the modified manual, and provided that the entire
           resulting derived work is distributed under the terms of a
           permission notice identical to this one.

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           Permission is granted to copy and distribute translations of this
           manual into another language, under the above conditions for
           modified versions, except that this permission notice may be
           stated in a translation approved by the Free Software Foundation.

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